package opengl.scenes;

import javax.microedition.khronos.egl.EGL10;
import javax.microedition.khronos.egl.EGL11;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.egl.EGLContext;
import javax.microedition.khronos.egl.EGLDisplay;
import javax.microedition.khronos.egl.EGLSurface;
import javax.microedition.khronos.opengles.GL;
import android.view.SurfaceHolder;

/**
 * An EGL helper class.
 */

public class EglHelper {
        public EglHelper() {

        }

        /**
         * Initialize EGL for a given configuration spec.
         * @param configSpec
         */
        public void start(int[] configSpec){
            /*
             * Get an EGL instance
             */
            mEgl = (EGL10) EGLContext.getEGL();

            /*
             * Get to the default display.
             */
            mEglDisplay = mEgl.eglGetDisplay(EGL10.EGL_DEFAULT_DISPLAY);

            /*
             * We can now initialize EGL for that display
             */
            int[] version = new int[2];
            mEgl.eglInitialize(mEglDisplay, version);

            EGLConfig[] configs = new EGLConfig[1];
            int[] num_config = new int[1];
            mEgl.eglChooseConfig(mEglDisplay, configSpec, configs, 1,
                    num_config);
            mEglConfig = configs[0];

            /*
            * Create an OpenGL ES context. This must be done only once, an
            * OpenGL context is a somewhat heavy object.
            */
            mEglContext = mEgl.eglCreateContext(mEglDisplay, mEglConfig,
                    EGL10.EGL_NO_CONTEXT, null);

            mEglSurface = null;
        }

        
        /*
         * Create and return an OpenGL surface
         */
        public GL createSurface(SurfaceHolder holder) {
            /*
             *  The window size has changed, so we need to create a new
             *  surface.
             */
            if (mEglSurface != null) {

                /*
                 * Unbind and destroy the old EGL surface, if
                 * there is one.
                 */
                mEgl.eglMakeCurrent(mEglDisplay, EGL10.EGL_NO_SURFACE,
                        EGL10.EGL_NO_SURFACE, EGL10.EGL_NO_CONTEXT);
                mEgl.eglDestroySurface(mEglDisplay, mEglSurface);
            }

            /*
             * Create an EGL surface we can render into.
             */
            mEglSurface = mEgl.eglCreateWindowSurface(mEglDisplay,
                    mEglConfig, holder, null);

            /*
             * Before we can issue GL commands, we need to make sure
             * the context is current and bound to a surface.
             */
            mEgl.eglMakeCurrent(mEglDisplay, mEglSurface, mEglSurface,
                    mEglContext);


            GL gl = mEglContext.getGL();
            
            return gl;
        }

        /**
         * Display the current render surface.
         * @return false if the context has been lost.
         */
        public boolean swap() {
            mEgl.eglSwapBuffers(mEglDisplay, mEglSurface);

            /*
             * Always check for EGL_CONTEXT_LOST, which means the context
             * and all associated data were lost (For instance because
             * the device went to sleep). We need to sleep until we
             * get a new surface.
             */
            return mEgl.eglGetError() != EGL11.EGL_CONTEXT_LOST;
        }

        public void finish() {
            if (mEglSurface != null) {
                mEgl.eglMakeCurrent(mEglDisplay, EGL10.EGL_NO_SURFACE,
                        EGL10.EGL_NO_SURFACE,
                        EGL10.EGL_NO_CONTEXT);
                mEgl.eglDestroySurface(mEglDisplay, mEglSurface);
                mEglSurface = null;
            }
            if (mEglContext != null) {
                mEgl.eglDestroyContext(mEglDisplay, mEglContext);
                mEglContext = null;
            }
            if (mEglDisplay != null) {
                mEgl.eglTerminate(mEglDisplay);
                mEglDisplay = null;
            }
        }

        public int getError () {
        	return mEgl.eglGetError();
        }
        
//        public void setGLWrapper(GLWrapper glWrapper) {
//            mGLWrapper = glWrapper;
//        }
//        private GLWrapper mGLWrapper;
        
        EGL10 mEgl;
        EGLDisplay mEglDisplay;
        EGLSurface mEglSurface;
        EGLConfig mEglConfig;
        EGLContext mEglContext;
    }
